Some of the prior art cable laying plow blades have no replaceable cutting edges and when the edges are dulled the blades have to be disgarded or rebuilt.
Some of the prior art plows were provided with replaceable sharp edge members, but they typically were made in expensive-to-machine configurations and were adapted to fit over the permanent blade fixtures. A search of the patent literature discloses a number of such replaceable blades. For example, U.S. Pat. No. 3,170,300 to Kelley, illustrates a replaceable blade 66 which fits over the plow shank. Replaceable blade 66 is generally V-shaped, having four external surfaces. Such a configuration requires substantial expensive machining and is therefore impractical from an economical point of view. Similarly shaped replaceable blades are shown in U.S. Pat. No. 3,497,016; U.S. Pat. No. 3,341,253; and U.S. Pat. No. 3,377,500.
The following patents disclose blades and/or replacements less pertinent to the present invention than those described above:
U.S. Pat. No. 4,142,817, Lazure PA1 U.S. Pat. No. 1,668,277, Kirby PA1 U.S. Pat. No. 1,351,376, Dillon PA1 U.S. Pat. No. 970,818, Harryman PA1 U.S. Pat. No. 796,225, Klingberg PA1 U.S. Pat. No. 323,770, Zeek